This invention relates to the rapid fabrication of prototypes, and in particular to molding these prototypes in composite, structural plastics.
In today's rapidly changing technological environment the ability to move from the conception of a product to full scale product development in as short a period of time as is possible is obviously of critical importance in many industries. In most cases this involves an early step of producing at least a non-functional, visual display prototype of the object(s) to be manufactured. Prior to recent computer developments in prototyping, wood forms would be machined to provide the form of the object so that a wax, plastic or rubber mold could be quickly made in order to produce at least a few three dimensional objects to simulate the final article to be manufactured. Today, computer aided design (CAD) is frequently employed for at least rapid visualization of an article to be manufactured. While enormously useful to engineers studying the best production methods for the object, CAD has been further improved so as to actually produce a three dimensional object for handling, visualization, and even limited suitability testing. These CAD techniques include steriolithography (SLA); laminated object manufacturing (LOM); selective laser sintering(SLS); fused deposition modeling(FDM) and solid ground curing (SGC). These techniques use either powder, liquid or sheets of polymers or other materials and are sequentially formed together, eventually producing a prototype of the desired object. For virtually all of these rapid prototype fabrications, including the prior "soft tooling", and the up to the minute CAD prototype production methods, the result is a prototype with relatively low temperature resistance and strength. While extremely useful at the early visual stage of product development, these prototypes cannot be used to fully evaluate the functionality of a finished product.
Obviously if a material and casting process were developed so that a structural part with equivalent functional properties to the ultimate finished product could be easily prototyped, such as, for example, utilizing the above soft tooling or CAD prototype production methods, a major breakthrough in reducing the design cycle, time-to-market would be accomplished. However, because of the temperatures of most molten metals or the heat and pressure required for structural grade, fiber reinforced plastics, this has heretofore been impossible. Additionally, if this material and casting process could be used in the fabrication of the molds themselves, prototype and production runs would greatly benefit by the elimination of costly "hard" steel tooling, mold costs.
A typical example of current, prototype fabrication can be found in the automobile industry. If a prototype of an intake manifold, for example, is required, an initial model would be made most probably using steriolithography (SLA). However, to test the functionality of such a prototype, automotive design engineers then have to make a steel mold and inject nylon to produce that design in plastic so it will withstand high temperatures and stresses. A one step, inexpensive procedure, would, of course, offer important economic advantages.
In copending U.S. application Ser. No. 08/714,813, now U.S. Pat. No. 5,849,229, the disclosure of which is hereby incorporated by reference, a method for molding composite, structural plastic objects in molds traditionally used in foundries for molding metal parts is described. This same basic method can be employed in the present invention to produce not only inexpensive prototypes utilizing soft tooling or the developing, rapid prototyping techniques, but also to form molds suitable for structural, prototype or final product fabrication. Thus a low cost and rapidly developed, molded prototype part can be used by design engineers not only to visualize the object in a hands-on, three dimensional representation, but also to test the object in the actual environment to which the finished product is going to be exposed. Extremely important cost savings are realized both in fabrication of the prototype and in time saved in bringing a new product to market.
It is therefore a primary object of the invention to provide a low cost method for producing structural, composite plastic prototype parts.
An additional object of the invention is to provide a method for utilizing soft tooling and modern day, rapid prototyping techniques in order to fabricate structural, composite plastic prototype parts.
A further object of the invention is to provide a method for utilizing molds fabricated in wax, plastic, plaster, rubber, or spray metal in order to produce structural, composite plastic prototype parts.
An additional object of the invention is to provide a simple, low cost, one step method for producing a prototype part having equivalent visual and structural characteristics to the actual part to be commercially produced.
A further object of the invention is to provide a high temperature, high strength, composite, structural plastic mold for prototype and production runs.